Secure optical information disc having a minimized metal layer

ABSTRACT

A secure optical data disc comprising an electronic article surveillance tag embedded within a layered disc structure comprising first and second substrates is disclosed. The tag is placed within a non-readable zone (i.e., one that does not have data tracks) of the secure disc. To improve signal quality of the tag, the reflective metal layer thickness is minimized and discontinuities are introduced on the reflective metal layer. A first discontinuity separates a data track region of the disc from a mirror/ID band region. A second, radial discontinuity opens the mirror/ID band ring.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Bigley, U.S. ProvisionalPatent Application Ser. No. 60/455,284, filed on Mar. 17, 2003, andBigley, U.S. patent application Ser. No. 10/792,352, filed on Mar. 3,2004, entitled “Secure Optical Information Disc,” the contents of bothreferenced patent applications are incorporated herein by reference intheir entirety, including any references therein.

TECHNICAL FIELD

This invention generally relates to electronic data storage media suchas those used to store music, movies, software (including games), andother valuable electronic data assets distributed through retail and/orrental outlets. More particularly, the invention relates to themanufacture of optical data storage discs for carrying an electronicallydetectable security tag. The security tag potentially embodies a varietyof electronic article surveillance (EAS) technologies including onesthat generate specific identification codes for inventory control (e.g.,RFID and smart tags) as well as ones that, unless deactivated, resonateat a particular frequency (or range) and activate an alarm when passedthrough an electronic surveillance gate.

BACKGROUND

Optical data storage discs are the predominant media for storing music,movies and software (including general PC software as well as video gamesoftware played upon game consoles connected to televisions/monitors)distributed via retail outlets. Today, music is encoded on an opticaldata storage disc using compact disc (CD) technology. Software that isdistributed through retail outlets is also typically stored on opticaldata storage discs embodying the CD technology. Movies and games(executed on game consoles) are encoded on optical data storage discsusing digital versatile disc (DVD) technology that holds significantlymore data than a CD.

Retail theft of optical data storage discs storing valuable digital dataassets has received considerable attention from retailers. Initially,theft was deterred through the use of bulky, six by 12 inch cardboardboxes that were difficult for shoplifters to conceal. Later, equallybulky, plastic frames were placed around the boxes to deter theft. Whilesuch packaging was an effective deterrent, it created substantial solidwaste. Thus, the bulky boxes were abandoned and today, CDs are generallypackaged in the well-known “jewel” case. Similarly, DVDs for movies aregenerally displayed for retail customers within slightly larger plasticcases including one or more optical data storage discs. On the otherhand, retailers have resorted to placing DVDs containing game consolesoftware in locked cabinets to deter theft.

In the 1990s electronic security mechanisms replaced bulky packaging asa means for discouraging/controlling retail theft. In particular,electronic surveillance tags are now placed on/within optical discstorage retail packaging. Unless deactivated at the checkout counter,the security tags are sensed by surveillance panels positioned at theentrance/exit of a retail establishment. If not deactivated, sensorswithin the panels detect the security tag when a person attempts toleave with the case containing the security tag and an alarm isactivated. A number of such security tag technologies are well known inthe art.

Currently electronic security tags are attached to a case within which aDVD, for a movie or game, is held. If the case is taken from a retailestablishment before the security tag is deactivated, then an alarmsounds when the security tag passes through security panels at the door.A shortcoming of attaching security tags to a package/case containing anoptical disc is that a shoplifter need only remove the disc from thepackage (or remove the security tag from the package) to evade detectionby security panels placed at a store's exit. As a consequence, retailerscontinue to maintain their game software within locked cases.Alternatively, and apparently to address the shortcomings of attaching asecurity tag to a CD case, attaching a security tag to a CD disc havinga single substrate has been proposed a number of times in the prior art.These previous proposed CD structures have yet to be adoptedcommercially by retailers. Introducing a security tag introduces thepossibility that the security tag will interfere with playing the discby a purchaser of the disc. One problem arising from attaching asecurity device directly to a disc is the need to maintain balance.Another restriction is that incorporating a security tag onto the discitself should not cause the disc to no longer meet specifiedspace/dimension standards for the particular optical data storage media.

Yet another potential challenge of incorporating a security tag intostorage media is providing a sufficiently strong signal, by the securitytag, for sensing by a security gate. The security tag must fit within arelatively small space. However, the reduced size inevitably leads tothe security tag transmitting a weaker signal.

SUMMARY OF THE INVENTION

The present invention is directed to a secure disc arrangement andmethod for manufacturing the secure disc such that a resulting opticaldisc is produced in a manner: conforming to the space limitations of theoptical disc media standards organizations, providing a sufficientlystrong signal to ensure detection of a security tag embedded in the hubof the optical disc media, and meeting the production throughput/timingrequirements of manufacturers—thereby providing both a technological aswell as commercially acceptable solution to a need to control theft ofmovies, programs and games stored upon optically encoded media (e.g.,DVDs) comprising a metalized layer that potentially interferes withsensing a signal generated by the security tag.

The present invention thus comprises a secure optical data storage disc.The secure disc includes a first substrate. The substrate, by way ofexample, is formed by injecting molten plastic within a mold. The securedisc has a non-readable zone that does not include data tracks (disposedupon a readable surface of the disc). The security tag is disposedwithin the non-readable zone of the disc and thus does not interferewith reading the data tracks. The metalized layer thickness issubstantially reduced in comparison to previously manufactured discs.Reducing and minimizing the metalized layer thickness reduces itsshielding effect upon signals generated by the security tag that aresensed by a security gate at a retail establishment.

Furthermore, in accordance with more particular embodiments of theinvention where a metalized ID band is present (as opposed to asemiconductor or non-conductive ID band), discontinuities are introducedwithin metalized areas of the secure disc to reduceinterference/shielding of the signals generated by security tags. First,a disruption is introduced between an outer portion of the disccontaining the optically sensed digital data tracks and an inner portioncomprising the ID band (also referred to as the “mirror” band). Also, aradial disruption is introduced in the ID band itself to further improvethe ability of a security gate to sense the signal generated by thesecurity tag. The aforementioned gaps need not be introduced in the casewhere the mirror band is made up of semiconductor (e.g., silicon) ornon-conductor materials.

The format and layering of the data tracks differs in accordance withvarious embodiments of the invention.

The present invention is intended to encompass a variety of opticallyencoded discs carrying a variety of information assets within areflective/semi-transmissive layer carried on one or more substrates.The invention is embodied, for example, within DVDs that are encodedwith movies, videogame console game software, and software in general.Such embedding prevents separation of a disc from its EAS tag and assuch provides a significantly higher barrier to circumvention, bywould-be shoplifters, than other known arrangements that merely embedthe tag within a case. The present invention is intended to be carriedout through the use of a variety of thin film EAS technologies arrangedin a variety of topologies and circuits. The invention will bedescribed, by way of illustrative examples, further herein below.

BRIEF DESCRIPTION OF THE DRAWINGS

While the appended claims set forth the features of the presentinvention with particularity, the invention, together with its objectsand advantages, may be best understood from the following detaileddescription taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a schematic plan view of an exemplary secure disc comprisingan annular security tag sandwiched between two substrates of an opticaldisc and located within the non-data region of disc;

FIGS. 2 a-2 c are cross-sectional views of various types of secure DVDdisc formats;

FIGS. 3 a-d are a set of plan views of various security tag coilconfigurations;

FIGS. 4 a-4 b are DVD layer summaries for an initial molding stage forDVD-14 and DVD-18 formats;

FIGS. 5 a-5 b are DVD layer summaries for an intermediate (stripped)stage for DVD-14 and DVD-18 formats;

FIGS. 6 a-6 b are DVD layer summaries for a final assembly stage forDVD-14 and DVD-18 formats;

FIG. 7 is a plan view of an assembly line for carrying out DVDmanufacturing in accordance with an embodiment of the present invention;

FIGS. 8 a-8 b summarizes exemplary fabrication stages for DVD-5 andDVD-9 discs comprising security tags embedded between two substrates;and

FIGS. 9 a-9 b illustratively depict (by comparison to a prior art disc)additional features of a minimized metal disk that enhances sensing asignal generated by the security tag embedded within a secure disc inaccordance with embodiments of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

A secure disc, including all formats (e.g., CD, DVD, etc.), comprises,by way of example and not limitation, a security tag sandwiched betweenfirst and second substrates of the secure disc (or alternatively placedwithin an recess on a single substrate and covered by a lacquer layer).At least an antenna portion of the security tag occupies a region of thedisc that is not encoded with optically sensed data. The location of thesecurity tag avoids interfering with optically sensed data stored uponthe secure disc. In exemplary embodiments, the security tag issandwiched between first and second substrates at a location near thehub of the secure disc (e.g., within a clamping region, and potentiallyextending into a mirror band area).

Furthermore, the security tag is substantially balanced with regard to arotational axis of the secure disc. In an embodiment of the inventionthe security tag is ring-shaped (i.e., defined by concentric circularinner and outer edges). Thus, when concentrically embedded/sandwichedbetween two substrates of the secure disc, the thin film security tagneither unbalances the disc nor interferes with data acquisition fromthe disc.

The present invention contemplates a variety of thin film EAS sensortechnologies/topologies. In particular embodiments of the invention, thesecurity tag is provided in the form of an insulated thin filmresonating device including capacitively coupled coiled circuits,carried by an insulating thin film, constituting an inductor/capacitor(LC), or resonant, circuit. The insulating thin film establishes thecapacitive aspect of the LC circuit by slightly offsetting pairs ofmetallic coils that make up the security tag. The paired coils of thesecurity tag have sufficient surface area to resonate when exposed toelectromagnetic energy at a frequency within a particular frequencyrange. Alternatively, a separate capacitor circuit, separate from themetallic coils, provides at least a portion of the capacitive aspect ofthe security tag.

The signal generated by the security tag sandwiched between the twosubstrates of an optical data storage disc is detected by a receivingantenna thereby making it a viable electronic article surveillanceanti-theft device capable of discouraging theft of the optical datastorage disc. Additional features reduce the interference/shieldingeffect of the metalized layer of the optical data storage disc on asignal generated by the coil of the security tag. Such features includethe metalized reflective data layer (to produce a minimized metal disc)having a substantially reduced thickness. Yet another signal-improvingfeature includes a first (e.g., concentric) discontinuity introducedbetween the ID band and the digital data tracks on a reflective metallayer of the disc. Still another source for improved security tag signaltransmission comprises a radial discontinuity introduced in the ID banditself.

Turning to the drawings, and in particular FIG. 1, the invention ispresented in the form of a secure optical data storage disc 100 (alsoreferred to herein as “secure disc 100”) that comprises a security tag102 sandwiched/embedded between a first and second substrate. Ingeneral, the tag occupies a non-readable surface area on the disc 100.In the illustrative embodiment, based upon DVD standard dimensions, thesecurity tag 102 comprises a thin film LC resonating device thatresides, by way of example, primarily within an annular clamping area106 of the secure disc 100 (and centered with regard to the axis ofrotation of the disc 100). The clamping area 106 is defined by a ringwith an inner diameter of 22.0 mm and an outer radius of 33.0 mm.

The size/dimensions of the security tag 102 are generally bound by therequirement that it does not interfere with reading encoded data—andshould not be shielded by a metal layer, and therefore at least theantenna portion of the security tag 102 occupies non-readable regions ofthe secure disc 100. Thus, in embodiments of the invention, at least aportion of the security tag 102 extends beyond the clamping area 106 toother regions of the disc 100. For example, in an embodiment of theinvention the security tag extends into an annular portion 108 of thesecure disc 100 having an inner diameter of 15.0 mm and outer diameterof 22.0 mm. However, the tag 102 does not extend over the rim of thecenter hole (at a radial distance of 15.0 mm. from the rotational axisof the disc 100). In this embodiment the security tag 102 occupies anarea from 15.0 mm to 36.0 mm (just outside a stacking ring 110, ifpresent, at a diameter of 33.5 mm) thereby enhancing the signal strengthof the security tag.

Furthermore, to provide a stronger signal, in alternative embodiments ofthe invention, the outer edge of the surface area of the security tag102 is potentially extended into a non-readable region beyond thestacking ring 110 diameter (33.5 mm)—a concentric ring having an innerdiameter of 38.0 mm. and outer diameter of 44.0 mm. (see, FIG. 9 b).This region is referred to as the mirror/ID band region of the disc. Onthe other hand, in such alternative embodiments of the invention, thesecurity tag 102 does not extend beyond the mirror-band region into areadable region 112 of the secure disc 100 so as to obscure readabledata tracks that begin at a diameter of 45.0 mm and end at a diameter of118 mm in the illustrative embodiment since the coil/antenna is not tobe shielded by a metal layer. However, in embodiments of the invention,certain non-radiating circuit components of the security tag 102, suchas a capacitor or diode, may be hidden under the mirror band, to fullyutilize available space to maximize the signal strength of theresonator.

The mirror band region contains information that is visually orelectronically scanned to provide information. In the case of a DVD withtwo content-laden substrates, two barcodes are provided. The barcodesare offset so that a barcode reader can access both barcodes from oneside of the disc. The mirror band is isolated from the portion of themetal layer constituting the data portion of the disc through doublemasking—i.e., a first mask is used to sputter the data tracks, and asecond mask is used to sputter the mirror band such that a concentric(ring) disruption is introduced between the metalized data track regionand the metalized mirror band that layer-wise fall within a same layerof an optically sensed disc. The second sputtering step deposits a layerof metal for the mirror band that is thicker than the metal layer forthe data tracks.

As will be evident to those skilled in the art, the above-describedexemplary embodiment can be modified in a number of ways, including,without limitation modifying: any of the identified dimensions(including the disc itself), the size of the security tag 102, the typeof encoding of data on the disc (e.g., CD, DVD, etc.), the type ofinformation encoded/embodied in the security tag (e.g., an RFID tagproviding a value corresponding to the particular disc—as opposed tomerely resonating at a particular frequency to which a sensor is tuned),and the type of data on the data tracks of the disk (e.g., movies,games, application programs, music, etc.). Such modifications areintended to fall within the scope of the present invention.

Turning to FIGS. 2 a-d, partial cross-sectional views are provided offour exemplary types of secure DVD discs 200 a-d. These simplifiedcross-sectional views (corresponding to a side view of the secure disc100, when quartered) depict the general location of a security tag 202within the layers of exemplary secure disc structures. The security tag202, by way of example, comprises a polypropylene or polyethylene/Mylarbacking material imprinted with a metallic coil circuit. In anembodiment of the invention, the security tag 202 includes a capacitordevice that is short-circuited during deactivation (at the checkoutcounter). Suitable manufacturers of such tags are All-Tag Security S.A.Z.A.E. of Belgium and Checkpoint Systems, Inc. of Thoroughfare, N.J.

In an exemplary embodiment of the present invention (the invention ispotentially incorporated into any appropriate optical information disctype), the security tag 202 is embedded within any of a variety of DVDsconforming to the following dimensions. By way of example, eachsubstrate is approximately 0.6 to 0.5 mm. (but may be thinner toaccommodate multiple readable layers on a side) in the portion of thedisc where optically sensed information is located. A bonding layer 204,used to hold the two substrates (including their reflective/transmissivedata layers) together, is approximately 0.1 mm (0.04-0.07 mmrecommended). As shown in FIGS. 2 a and 2 b, the non-readable area ofone or more of the substrates may be thinner to accommodate thethickness of the security tag 202. Furthermore, as shown in FIGS. 2 aand 2 b, the bonding layer 204 potentially extends nearly all the way tothe center hole—and the bonding/adhesive material making up the bondinglayer 204 potentially covers both the top and bottom of the security tag202. Therefore the total thickness of the DVD structure, regardless ofreadable data layer format, is approximately 1.20 mm. (+0.30 mm/−0.06mm). In yet other embodiments, such as BLUE RAY discs, the singlesubstrate is approximately 1.19 mm. The disc, by way of example has anouter diameter of 120.00 mm (+/−0.30 mm), and the center hole has adiameter of 15.00 mm (+0.15 mm/−0.00 mm). The values in parenthesesrepresent tolerances specified by the standard, ECMA-267 3^(rd) Edition,April 2001, for 120 mm DVD read-only discs. In other embodiments, theouter diameter of the disc is substantially less than 120 mm., and inyet other embodiments the substrates/media are non-circular (butbalanced in relation to a rotational axis). The above-specifieddimensions and tolerances are intended to be exemplary and differ inalternative embodiments of the invention.

In an embodiment of the invention, the security tag 202 islocated/embedded within a space/layer of a secure disc referred toherein as the bonding/adhesive layer 204 having a thickness ofapproximately 0.10 mm. A suitable manufacturer of a bonding resin forthe bonding/adhesive layer 204 is Nagase California Corp. of Sunnyvale,Calif. The bonding/adhesive layer 204 is sandwiched between first andsecond polycarbonate substrates 208 x and 210 x of a secure DVD disc.Suitable polycarbonate material is provided by Teijin Kasei America ofAlpharetta, Ga. The tag 202 preferably includes glue on at least oneside to aid its placement on the disc. However, the glue can be placedon both sides to ensure secure bonding of the tag 202 and substrates ofthe disc. If only on one side, then resin flows over the opposing sidebefore the two substrates are bonded together to form the disc.

Yet another embodiment of a secure disc including a minimized metallayer is based upon an optical information disc structure referred to asa BLUE RAY disc. A BLUE RAY disc (read by means of a blue laser beam)comprises a single substrate (approximately 1.19 mm thick). Data tracksare formed on a first surface of the substrate. A very thin, minimized,metal layer is deposited upon first surface of the substrate to form theoptically readable surface. The minimized metal layer, in the instanceof a BLUE RAY disc, is on the order of 40 nanometers or less—such thatthe metal layer does not effectively prevent reading the security tag bysensor panels in a retail establishment (e.g., as specified by amanufacturing standard). Thereafter, a thin lacquer coating (e.g.,approximately 0.01 mm thick) is applied to the sputtered minimized metallayer. The data tracks are read through the relatively thin lacquercoating rather than the relatively thick substrate. In this particulararrangement, the tag 202 is placed within a molding cavity prior toinjecting polycarbonate that forms the single substrate of the BLUE RAYdisc. The polycarbonate flows over the tag and embeds/encapsulates thetag within the relatively thick substrate. In yet other embodiments, thesubstrate of a BLUE RAY disc is formed from two separate substrates thatare thereafter bonded together to facilitate sandwiching the securitytag 202 within the layers of the disc formed by the two separatesubstrates.

As demonstrated in the various embodiments of the secure disc depictedin FIGS. 2 a-c, the substrates are either “blank” or alternatively carryone or more metalized/reflective layers depending upon the disccapacity. It is noted that in illustrative embodiments of the inventionat least one of the substrates 218 x and 210 x is potentially “thinner”near the center hole. This accommodates a portion of the security tag202's thickness (approximately 0.02 mm) that exceeds the thickness ofthe bonding/adhesive layer 204 x. In embodiments of the invention, thetwo substrates are separately processed, and at a point just prior tobonding the two substrates 218 x and 210 x together, the security tag202 is placed upon one of the two substrates. Thereafter, the twosubstrates are bonded together using any appropriate bonding/adhesivematerial which forms the bonding/adhesive layer 204 x. It is noted thatthe views depicted in FIGS. 2 a-c are not to scale, but are intended toshow the general layers of various embodiments of a secure discembodying the present invention.

FIG. 2 a depicts a schematic cross-sectional view of a secure disc 200 areferred to as a DVD-5 along with suggested/exemplary dimensions—thatmay vary in accordance with various embodiments of the invention. TheDVD layers/format depicted in FIG. 2 a is used for DVD's that carry avariety of encoded data including, by way of example, movies and gameconsole-based video game software. The disc 200 a generally depictslayered structures specified for a single-sided, single readable layerDVD-5 disc. In the illustrative example the DVD-5 disc 200 a includes asingle reflective layer 206 a (approximately 30 nm thick) of aluminum.The thickness varies in accordance with various embodiments of theinvention. A range of 29-33 nm thickness for the reflective layer 206 aprovides acceptable results and balances the need to the shieldingeffect of the reflective layer and the need to provide a reliablyreflective surface.

The security tag 202 (up to, for example, approximately 0.3 mm. thickincluding possibly backing and/or application glue layers) issandwiched, along with a bonding/adhesive layer 204 a (approximately0.07 mm.), between a blank (dummy) substrate 208 a (approximately 0.6mm.) and a non-blank substrate 210 a (approximately 0.5 mm.) upon whichthe single reflective layer 206 a is deposited. It is specifically notedthat the above layer thicknesses are provided for illustrative purposesand should not be construed as limiting the present invention. Forexample, modifications to the tag 202 thickness potentially influencethe thickness of the substrate and bonding resin layers. The reflectivelayer 206 a is, by way of example, aluminum. In embodiments of theinvention the blank substrate 208 a optionally includes printed artworkon its outer non-readable surface 212. Finally, it is noted that in theillustrative embodiments, the substrate 210 a thins beginning at point213 of a non-readable portion adjacent to a center hole 215. The widthdifference in substrate 210 a (e.g., approximately 0.01 to 0.02 mm.)accommodates a difference in the thickness of the security tag 202 andthe bonding/adhesive layer 204. While not specifically depicted in FIG.2 a, the tag 202 is bonded to one, or both, of the substrates 208 a and210 a with an adhesive (approximately 5 microns thick).

FIG. 2 b depicts a schematic cross-sectional view of a secure disc 200 bthat incorporates the layered structures specified for a single-sided,dual readable layer DVD-9 disc. In the illustrative example the DVD-9disc 200 b includes a reflective layer 206 b (e.g., approximately 30 nm)sputtered on a stamped substrate 208 b, and a semi-transmissive layer207 b (approximately 10 nm), of gold, silver, silver alloy or silicon,that is sputtered on a stamped substrate 210 b. An exemplary range forthe thickness of the semi-transmissive layer 207 b is 8-12 nm. Thus, inembodiments of the invention the reflective layer 206 b is substantiallyreduced (“minimized”) to reduce the shielding effect of the metal layerson the signal transmitted by the tag 202 when energized. The securitytag 202 occupies a layer of the DVD structure that is also occupied by atransparent bonding/adhesive layer 204 b between the stamped substrate208 b which carries the reflective layer 206 b, and thesemi-transmissive layer 207 b sputtered upon the substrate 210 b.Methods for fabrication of the two readable layers on a single side of aDVD-9 disc are known to those skilled in the art. In exemplaryembodiments of the invention, the reflective layer(s) are aluminum andthe transmissive layer(s) are gold, silver, silver alloy, or silicon.The layer thicknesses for the DVD-9 structure are generally the same asthe ones described above for FIG. 2 a.

FIG. 2 c depicts a schematic cross-sectional view of a secure disc 200 cthat incorporates the layered structures specified for a double-sided,dual readable layer DVD-18 disc. In the illustrative example the DVD-18disc 200 c includes on a first readable side: a reflective layer 206 c,a transparent bonding layer 209 c and a semi-transmissive layer 207 cfabricated on/attached to substrate 210 c. The second readable sideincludes: a reflective layer 216 c, a transparent bonding layer 219 cand a semi-transmissive layer 217 c fabricated on/attached to substrate208 c. While not specifically depicted in FIG. 2 c, protective layers(see FIG. 6 a and FIG. 6 b) are spin coated on their respective halvesof the disc 200 c to protect the reflective metal layers. Thereafter,the secure tag 202 is placed upon one of the two halves of the DVD-18corresponding to substrates 208 c and 210 c. Finally, the two halves arebrought together to form a layered structure wherein the security tag202 occupies a layer of the DVD structure that is also occupied by thebonding/adhesive layer 204 c between the protective layers. In yetanother embodiment, the security tag 202 is placed between substratehalves of a dual-readable side DVD-14 structure. It is noted that, inthe illustrative embodiment, the thickness of the metal and bondinglayers are sufficiently thick in the DVD-18 structure such that a changein substrate thickness is not needed at point 213. In other embodimentsthe thickness of one or more of the two substrates is thinned at aportion where the tag is placed to accommodate the tag thickness.

Turning briefly to FIGS. 3 a-d, a set of exemplaryconfigurations/geometries for the security tag are provided. Asexplained previously above, the security tag fits, by way of example,within the clamping area of a DVD or other optically readable datastorage disc. The coils of the security tag can take any of a number ofshapes and sizes—subject to the space limitations imposed by the discgeometry. FIGS. 3 a, 3 b and 3 c schematically depict embodiments ofminiature coil configurations. In these embodiments signal strength isenhanced by creating multiple replicated coil pairs and distributing thecoils around the perimeter of a ring substrate for the security tag 202.FIG. 3 d, on the other hand, derives signal strength through the use oflarge ring-shaped coils that conform to the ring-shape of the securitytag 202's substrate. Alternative embodiments of the invention utilizeother shapes/coil layouts.

Having described exemplary structural features of exemplary DVDstructures embodying the present invention, attention is directed to themethods for fabricating such structures. Referring to the sequence ofFIGS. 4 a-b, 5 a-b and 6 a-b, the process for manufacturing DVD-14 andDVD-18 disc structures is summarized by way of identifying the layers ateach of three primary stages. It is noted initially that a DVD-14 istwo-readable-side DVD having a DVD-9 readable side and a DVD-5 readableside bonded together. A DVD-18 has two DVD-9 readable sides bondedtogether. The overall thickness of the DVD discs conforms to the 1.20 mmthickness specification.

Generally, in order to maintain the overall thickness specification of1.20 mm. for a DVD, substrates used to fabricate the multiple readablelayers are stripped and discarded so that the combined thickness isstill 1.20 mm. To facilitate such stripping, an acrylic blank (that willrelease the aluminum without damaging the reflective layer) is used asthe substrate for the reflective layer. The process starts with themanufacturing of a DVD 9 and a DVD 5 combination for DVD-14 or twoDVD-9's for DVD-18. The information for the three readable layers forDVD-14 originates from three different stampers. Four stampers are usedto produce the readable layers for DVD-18.

FIGS. 4 a and 4 b illustratively depict the initial molding/bondingprocesses. When a DVD-14 is manufactured, the half disc for the DVD-5portion is molded. However, as shown in FIG. 4 b, it is not necessary tobond a blank substrate to the DVD-5 disc because it will eventually bebonded to the DVD-9 substrate. The DVD-9 substrates are manufactured inthe nearly same way as standard DVD-9's. However, the DVD-9 portion ofthe sandwich includes an acrylic layer for layer 1 instead of thestandard polycarbonate used for DVD-9. Acrylic is used for the layer 1substrate because it adheres poorly to aluminum.

The acrylic layer, which has the information molded into its surfacefrom a stamper, can be pealed off the substrate during a strippingprocess, leaving the information embossed in the cured bonding lacquerlayer with an aluminum surface. In principle, the acrylic substrate actslike a stamper as it is used to transfer the image of the pits into thecured bonding resin. The stripping process results in the layeredstructures described in FIGS. 5 a and 5 b. After the two DVD-9's in thecase of DVD-18 are made or a DVD-9 and DVD-5 are made in the case of DVD14, the DVD 9 portions go to the stripping process. The strippingprocess peals the acrylic substrates off the surface.

After stripping, the two disc halves are bonded together to yield atwo-sided disc with four layers (two per side) for DVD-18 or a two-sideddisc with three layers—two on one side and a single layer on theother—for DVD-14. A first step before the second bonding processcomprises spin coating the exposed aluminum sides of the previouslystripped disc halves with a CD-type UV protective coating. After thehalves are protective coated (two DVD-9 disc halves for DVD-18 or oneDVD-5 half and one DVD-9 half for DVD-14) the disc halves are bondedtogether. In accordance with an exemplary embodiment of the invention,the security tag 202 is applied to one of the two disc halves eitherduring molding of a substrate or alternatively after sputtering andprior to re-bonding. In a particular illustrative embodiment, while anindexing carousel transfers a disc half containing the reflective metallayer to the final bonding stage, rotation of the table is temporarilypaused and an applicator attaches (e.g., dispenses and tamps in place)the security tag 202 to the disc half prior to the application of thebonding resin and the final combination of the disc by a consolidatormachine. After the bonding step a clamping mechanism ensures that thetwo substrates are securely attached to the tag and that the securitytag 202 does not compromise the structural integrity of the secure disc200.

Once the disc halves are bonded together the security tag 202 cannot beremoved, yet the disc maintains all of the structural integrity ofnon-secure discs that do not include the security tag 202 embeddedbetween the two substrates. FIGS. 6 a and 6 b provide the finalconfiguration for the DVD-18 and DVD-14 formats. The security tag 202 iscontained in the second bonding layer.

Turning to FIG. 7 a portion of a DVD assembly line is depicted. Theillustrative set of machines manufactures either DVD-5 or DVD-9(depending upon whether both sides are stamped/sputtered). Eachsubstrate is initially produced by a molding/stamping sub-assembly 700or 702 by Meiki Molding of Nagoya, Japan. Alternative providers ofequipment include Singulus, of Kahl am Main, Germany. Transfer arms 704and 706 transfer the substrates to sputtering machines 708 and 710 madeby UNAXIS of Luxembourg, if the substrate is a non-blank substrate. Thesputtered or blank substrate is transferred by the transfer arms 704 and706 to an indexing carousel 712. In an embodiment of the invention,while the substrate is laying, inside face up, on the indexing carousel712 at position 714 (before applying a bonding resin and consolidatingthe two halves to form a single DVD, a tag applicator applies thesecurity tag 202 to one of the two halves. Thereafter, the DVD halvesare transferred by a transfer arm 716 to a consolidating assembly 718. Aflipper 720 flips one of the two disc halves in preparation forconsolidation while an applicator 722 applies bonding resin to the otherhalf. Thereafter, a consolidator 724 mates the two halves of the disc torender a DVD-5 or DVD-9 disc. Thereafter, a spinner spins excess bondingresin from the consolidated disc assembly and the resin is cured throughexposure to a UV light source. Inspection and printing stages completethe exemplary DVD assembly processes. The robotic transfer arms,indexing carousel 712 and components of the consolidating assembly 718are provided, for example, by Origin of Tokyo, Japan.

Turning to FIGS. 8 a and 8 b, a set of schematic flow diagramsillustratively depict the primary stages for creating replicated DVD-5and DVD-9 discs, respectively. These figures schematically depict twoalternative sequences of operations performed by the manufacturing linedepicted in FIG. 7. With reference to FIG. 8 a, a stamper line generatesan embossed substrate at stage 800. Thereafter, the reflective(aluminum) coating is applied (sputtered) at stage 802 to render thedata bearing half of the disc. It is during this stage that themirror/ID band is also applied by sputtering. However, appropriatemasking is utilized to introduce a discontinuity between the metal ofthe digital data portion of the disk and the metal for the mirror/IDband of the disk. An exemplary pattern of metalization is provided onFIG. 9 b (described below). At stage 804, while the disc half containingthe reflective metal layer is being transferred to a bonding stage 806,wherein the data half is mated with a blank substrate provided bymolding stage 807, the security tag 202 is applied to the “reflective”half. It is noted that in alternative embodiments of the invention, thesecurity tag 202 is initially applied to the blank half after moldingstage 807. It is further noted that in yet other, less preferred,embodiments, the tag 202 is embedded within either of the two substratehalves during either of the two injection molding stages 800 and 807.After the bonding stage 806, described in greater detail above withreference to FIG. 7, the disc is inspected at stage 808. Thereafter,printing is placed upon the blank side of the DVD during stage 810.

With reference to FIG. 8 b, a stamper line generates an embossedsubstrate at stage 820. Thereafter, the reflective (aluminum) coating isapplied (sputtered) at stage 822 to render one data bearing half of theDVD-9 disc—including the sputtered mirror/ID band as well. At stage 824,while the disc half containing the reflective metal layer is beingtransferred to a bonding stage 826, wherein the data half containing thereflective metal (Al) layer is mated with a second data half containinga semi-transmissive metal (Ag or Au) layer provided by stamper stage 827and semi-transmissive layer stage 829, the security tag 202 is appliedto the “reflective” half. It is noted that in alternative embodiments ofthe invention, the security tag 202 is initially applied to the“semi-transmissive” half after the semi-transmissive layer stage 829.However, for timing purposes, in an embodiment of the invention whereinone of the two sputtering processes takes longer than the other (e.g.,the semi-transmissive layer takes longer to produce than the reflectivelayer), the security tag is applied to the half that takes less time tocoat with a metal layer. It is further noted that in yet other, lesspreferred, embodiments, the tag 202 is embedded within either of the twosubstrate halves during either of the two injection molding stages 820and 827. After the bonding stage 826, described in greater detail abovewith reference to FIG. 7, the DVD-9 disc is inspected at stage 828.Thereafter, printing is placed upon the blank, non-readable side of theDVD-9 disc during stage 830.

Turning to FIGS. 9 a and 9 b, an exemplary plan view is provided of thelayout for a metalization layer on a secure information discincorporating the present invention. In particular, FIG. 9 b depictsdiscontinuities introduced on a metalization pattern on a disc tofacilitate improving the ability to sense the security tag 102 signalwhen passing through a security gate. FIG. 9 a depicts a prior artmetalization pattern for an optical data disc wherein a single,continuous layer of metal is provided for both the data tracks (beyondthe 45 mm. circular region) and the mirror/ID band (within the 45 mm.circular region). In contrast, a metalization layer of a disc embodyingthe present invention, depicted in FIG. 9 b, contains a firstdiscontinuity 900, in the form of a ring having an inner diameter of44.0 mm. and an outer diameter of 45.0 mm. The first discontinuity 900provides conductive separation between the metal making up a digitaldata portion 902 of the disc and metal making up a mirror/ID bandportion 904 of the disc. In the exemplary embodiment, the discontinuityis about 0.5 mm. However, other widths can be utilized in accordancewith alternative embodiments of the invention.

In further distinction from the prior art (FIG. 9 a), the metalizationpattern within the mirror/ID band portion 904 of the disc includes asecond discontinuity 906. The discontinuity 906, having a width (by wayof example and not limitation) of 0.1 to 1.0 mm, creates an opening inthe ring metalization pattern within the mirror/ID band portion 904 ofthe disc. The width of the discontinuity 906 varies in accordance withalternative embodiments of the invention. The second discontinuity 906in the metalization pattern of the disc, like the first discontinuity900, improves the ability of signal sensors to pick up a signaltransmitted by the (energized) security tag 102.

In view of the many possible embodiments to which the principles of thisinvention may be applied, it should be recognized that the embodimentsdescribed herein with respect to the drawing figures are meant to beillustrative only and should not be taken as limiting the scope ofinvention. Furthermore, the illustrative steps may be modified,supplemented and/or reordered (at least in part) without deviating fromthe invention. Therefore, the invention as described herein contemplatesall such embodiments as may come within the scope of the followingclaims and equivalents thereof.

1. A secure optical data storage disc comprising: a first substrate; areflective metalization layer disposed upon the first substrate, whereinthe reflective metallization layer is approximately 30 nanometers inthickness or less; and a non-readable zone comprising a security tag. 2.The secure optical data storage disc of claim 1 wherein the reflectivemetallization layer is less than 33 nanometers and greater than 29nanometers.
 3. The secure optical data storage disc of claim 1 whereinthe disc structure conforms to the structural specifications of a BLUERAY disc.
 4. The secure optical disc of claim 1 wherein the optical dischas only a single substrate, and wherein the security tag isencapsulated within the single substrate.
 5. The secure optical datastorage disc of claim 1 wherein the reflective metalization layercomprises a first discontinuity, thereby forming conductive isolationbetween a first portion corresponding to a digital data tracks regionand a second portion corresponding to a non-digital data tracks regionof the disc.
 6. The secure disc of claim 5 wherein the metalizationlayer comprises a second discontinuity that creates an opening in asubstantially complete ring corresponding to the second portion of themetalization layer.
 7. A method for manufacturing a secure optical datastorage disc comprising a first substrate and a non-readable zone thatis not occupied by data tracks, the method comprising: forming the firstsubstrate; depositing a reflective metalization layer upon the firstsubstrate, wherein the reflective metallization layer is approximately30 nanometers in thickness or less; and securing a security tag to thefirst substrate within the non-readable zone.
 8. The method of claim 7wherein the reflective metallization layer is less than 33 nanometersand greater than 29 nanometers.
 9. The method of claim 7 the datastorage disc structure conforms to the structural specifications of aBLUE RAY disc.
 10. The method of claim 7 wherein the optical disc hasonly a single substrate, and wherein the securing step comprisesencapsulating the security tag within the single substrate.
 11. Themethod of claim 7 wherein the reflective metalization layer comprises afirst discontinuity, thereby forming conductive isolation between afirst portion corresponding to a digital data tracks region and a secondportion corresponding to a non-digital data tracks region of the disc.12. The method of claim 11 wherein the metalization layer comprises asecond discontinuity that creates an opening in a substantially completering corresponding to the second portion of the metalization layer.